* Iron is a metal, and metals are excellent conductors of electricity and heat due to the free movement of electrons in their structure.

* Sulfur and carbon are nonmetals. While some forms of carbon (like graphite) can conduct electricity, they are generally much poorer conductors than metals.

* Tin is a metal, but it's a relatively poor conductor compared to iron.

In summary: Metals are the best conductors, and iron is a very good example of a conductive metal.